23,860 research outputs found
Electromagnetic Probes in PHENIX
Electromagnetic probes are arguably the most universal tools to study the
different physics processes in high energy hadron and heavy ion collisions. In
this paper we summarize recent measurements of real and virtual direct photons
at central rapidity by the PHENIX experiment at RHIC in p+p, d+Au and Au+Au
collisions. We also discuss the impact of the results and the constraints they
put on theoretical models. At the end we report on the immediate as well as on
the mid-term future of photon measurements at RHIC.Comment: 8 pages, 9 postscript figures, to be published in the Proceedings of
the Hard Probes 2006 conference (June 9-16, 2006, Asilomar, CA
Signs of Thermalization from RHIC Experiments
Selected results from the first five years of RHIC data taking are reviewed
with emphasis on evidence for thermalization in central Au+Au collisions at
GeV.Comment: 10 pages, 6 figure
Plans for Kaon Physics at BNL
I give an overview of current plans for kaon physics at BNL. The program is
centered on the rare decay modes K+ --> pi+ nu nubar and KL --> pi0 nu nubar.Comment: 10 pages, 8 figures. Uses espcrc2.sty. For the proceedings of HIF04:
High Intensity Frontier Workshop, La Biodola, Isola D'Elba, June 5-8, 200
A Rejoinder on Quaternionic Projective Representations
In a series of papers published in this Journal (J. Math. Phys.), a
discussion was started on the significance of a new definition of projective
representations in quaternionic Hilbert spaces. The present paper gives what we
believe is a resolution of the semantic differences that had apparently tended
to obscure the issues.Comment: AMStex, 6 Page
Projective Group Representations in Quaternionic Hilbert Space
We extend the discussion of projective group representations in quaternionic
Hilbert space which was given in our recent book. The associativity condition
for quaternionic projective representations is formulated in terms of unitary
operators and then analyzed in terms of their generator structure. The
multi--centrality and centrality assumptions are also analyzed in generator
terms, and implications of this analysis are discussed.Comment: 16 pages, no figures, plain Te
Alternative Descriptions in Quaternionic Quantum Mechanics
We characterize the quasianti-Hermitian quaternionic operators in QQM by
means of their spectra; moreover, we state a necessary and sufficient condition
for a set of quasianti-Hermitian quaternionic operators to be anti-Hermitian
with respect to a uniquely defined positive scalar product in a infinite
dimensional (right) quaternionic Hilbert space. According to such results we
obtain two alternative descriptions of a quantum optical physical system, in
the realm of quaternionic quantum mechanics, while no alternative can exist in
complex quantum mechanics, and we discuss some differences between them.Comment: 16 page
Master Functional And Proper Formalism For Quantum Gauge Field Theory
We develop a general field-covariant approach to quantum gauge theories.
Extending the usual set of integrated fields and external sources to "proper"
fields and sources, which include partners of the composite fields, we define
the master functional Omega, which collects one-particle irreducible diagrams
and upgrades the usual Gamma-functional in several respects. The functional
Omega is determined from its classical limit applying the usual diagrammatic
rules to the proper fields. Moreover, it behaves as a scalar under the most
general perturbative field redefinitions, which can be expressed as linear
transformations of the proper fields. We extend the Batalin-Vilkovisky
formalism and the master equation. The master functional satisfies the extended
master equation and behaves as a scalar under canonical transformations. The
most general perturbative field redefinitions and changes of gauge-fixing can
be encoded in proper canonical transformations, which are linear and do not mix
integrated fields and external sources. Therefore, they can be applied as true
changes of variables in the functional integral, instead of mere replacements
of integrands. This property overcomes a major difficulty of the functional
Gamma. Finally, the new approach allows us to prove the renormalizability of
gauge theories in a general field-covariant setting. We generalize known
cohomological theorems to the master functional and show that when there are no
gauge anomalies all divergences can be subtracted by means of parameter
redefinitions and proper canonical transformations.Comment: 32 pages; v2: minor changes and proof corrections, EPJ
Analysis Method for Jet-Like Three-Particle Azimuthal Correlations
Jet-like three-particle azimuthal correlations can discriminate various
physical scenarios that have been proposed to explain the observed strong
modification to two-particle azimuthal correlations. The three-particle
correlation analysis is notoriously difficult in heavy-ion collisions due to
the large combinatoric backgrounds. We describe the general idea behind the
jet-like three-particle azimuthal correlation analysis, with emphasis put on
the subtraction of the combinatoric backgrounds. We discuss in detail the
various systematic effects in such an analysis.Comment: This is the final published version in NIM
Remarks on a Proposed Super-Kamiokande Test for Quantum Gravity Induced Decoherence Effects
Lisi, Marrone, and Montanino have recently proposed a test for quantum
gravity induced decoherence effects in neutrino oscillations observed at
Super-Kamiokande. We comment here that their equations have the same
qualitative form as the energy conserving objective state vector reduction
equations discussed by a number of authors. However, using the Planckian
parameter value proposed to explain state vector reduction leads to a neutrino
oscillation effect many orders of magnitude smaller than would be detectable at
Super-Kamiokande. Similar estimates hold for the Ghirardi, Rimini, and Weber
spontaneous localization approach to state vector reduction, and our remarks
are relevant as well to proposed meson and meson tests of gravity
induced decoherence.Comment: 10 pages, plain Tex, no figure
- …